Re: [Linuxptp-devel] Optimal P, I constants

[Richard C. <ric...@gm...>]

On Tue, Apr 23, 2013 at 03:45:12PM +0200, Miroslav Lichvar wrote:
 
> This one is with 100us jitter, 10ppb/s wander and 1s interval. The
> best I constant now becomes impractical as it will take hours
> for the servo to converge.

What clock has 100us jitter? Are you trying to model time stamp error,
like in SW time stamping?

> I was wondering how useful it would be to have a new servo parameter
> for the Allan intercept and set the P, I constants automatically
> according the intercept and measured clock update interval. What do
> you think?

I would like to have a table of PI constants, with one pair for each
(reasonable) sync rate. I don't think these need to be tuned to
particular oscillator characteristics, but rather just for "typical"
hardware. Most people will not know what they have and will not be
able to measure the Allan deviation of their clock.

Your simulation results are interesting. Do you propose to find PI
values for different sync rates in this way?

Thanks,
Richard